An experimental and numerical study on particle deposition in a U-shaped ribbed cooling channel under high-temperature conditions

Gas turbine blades have internal cooling passages with complex shapes and tight spaces, allowing tiny particles in the cooling air to readily build up. The accumulation of these deposits causes a notable increase in fluid resistance and a pronounced degradation of overall thermal performance, thereby substantially reducing the thermal protection capability of the blade. In this study, high temperature deposition experiments were conducted in a representative internal U-shaped ribbed cooling channel commonly seen in actual engines. An analysis was carried out to clarify how the blockage ratios and inclination angles of the ribs affect deposition distributions and efficiency in the channel. Numerical simulations were performed to investigate the flow characteristics and particle migration trajectories within the channel. In conjunction with a mesh-conversion simulation technology, the evolution of aerothermal performance induced by deposition was further analyzed. Results revealed that though particle deposition shared similar spatial distribution patterns across different rib configurations, the deposition efficiency varied greatly, with high blockage ratio configurations being more susceptible to particle deposition. The maximum difference in deposition efficiency among the investigated rib configurations was 14.5%. The rib geometry had a strong impact on particle migration paths and spatial distributions of particle sizes by influencing the evolution of vortex structures within the channel. This, in turn, significantly affected the particle impact efficiency and ultimately led to distinct particle deposition characteristics. At a given Reynolds number, particle deposition generally increased flow resistance. For the configuration with a rib inclination angle of 30° and a rib height of 5 mm, the post-deposition friction factor increased by 44.3%, relative to the clean case. A comprehensive thermal performance assessment showed that, for the rib configuration exhibiting the highest deposition efficiency, the performance evaluation criterion decreased to 0.95. As the blockage ratio increased, the overall thermal performance of the channel was deteriorated.